Method of decarbonizing ferro alloys



Patented Feb. 5, H924.

iterates PATIENT cornice.

HUGE G. SICARD, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO UNITED STATEQ FERRO ALLOYS CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF DEOARBONIZING FERRO ALLOYS.

No Drawing.

To all whom it may concern:

Be it known that I, HUGH 0. 810mm, a citizen of the United States of America, and a resident of Niagara Falls, county of Niagara, and State of New York, have 1nvented a new and useful Method of Decarbonizing Ferro Alloys, of which the following is a full, clear, and exact description.

This invention is a process of bessemerizing high carbon ferro alloys so as to prevent the loss of metal by oxidation during the blowing of the alloy and to permit the burning out of the carbon to produce a low carbon ferro alloy.

My invention relates generally to a method of producing low carbon ferro alloys, or decarbonizing such ferro alloys, and more particularly to the production of low carbon ferro chromium, or the decarbonizmg of such ferro chromium alloys.

In the ordinary Bessemer process for producing steel, it is well known that a certain quantity of silicon is necessary which will give heat by its oxidation during the blowing, the silicon and manganese oxidizing first and the carbon last. It is also well known that the Bessemer process has been used for the manufacture of low carbon ferro alloys, such, for example, as ferro chromium, but the objection to the process is that a considerable percentage of the metal alloyed with the iron is oxidized as well as the carbon, thus causing serious loss by producing a low grade alloy.

By means of the invention herein described the metal in the alloy is protected from oxidation by means of the presence of titanium. In general, therefore, this invention is designed to overcome the difficulties of oxidation above referred to, and thereby produce a ferro alloy having any desired low content of carbon, or even producing, if desired, such ferro alloy with no percentage of carbon present. Many other advantages resulting from this invention will be evident to those skilled in the art.

For the purpose of describing my method of producing low carbon ferro alloys, I will refer to and describe the production of a low carbon ferro chromium alloy. It is to be understood, however, that this invention is not confined to that particular ferro alloy, since those skilled in the art Application filed March 15, 1922. Serial No. 544,026.

will readily see how it can be applied to various other ferro alloys.

' In practicing my invention as applied to a ferro chromium alloy, operate as follows:

In addition to the usual materials employed in making up the mixture for charging in an electric furnace for the production of ferro chromium I add suflicient carbon to make a carbon content of from 6% to 10%; sufiicient silicon to make a silicon content of from 1% to 6%, and a sufficient quantity of ti-taniferous ore, such as rutile or ilmenite, to give a titanium content varymg from 1% to 10%. In practice I have found some percentage variation of the tltanlum necessary since such percentage Wlll depend upon the length of time during which air will be blown into the mass of high carbon ferro chromium, and in turn, the carbon content in the alloy will also depend upon this percentage, it being possible to completely oxidize the carbon if absorbed. The carbon is added so that when the mixture is heated in the electric furnace the alloy thus produced and, subsequently, tapped from the furnace contains besides the ordinary constituents, high carbon ferro chromium, and a certain percentage of titanium the amount depending upon the proportion of the titaniferous ore added to the usual mixture.

This titaniferous mixture is then charged into an electric furnace of the arc type, large enough in capacity to permit of tapping into a ladle a suflicient quantity of the ferro chromium alloy, containing the silicon, carbon, and titanium as above described, to prevent a substantial chilling of such alloy.

Such described mixture is then smelted in the furnace and the molten metal is then tapped into a ladle and afterwards poured from the ladle into an ordinary steel convert'er, such as is used in steel foundry! prac' ticc. Afterwards the molten metal is blown preferably by means of a hot blast, but if the converter is kept hot with an oil burner when not in actual operation, a cold air blast may be used. During the filling of the converter with the molten metal some lime is added which will give a fluid slag, a silicotitanate of lime.

During the blowing of the metal the silicon luu lU-n

oxidizes first, then the titanium, and then the carbon. The resulting silica and titanium oxide combines with the lime to form a fluid silico-titanate of lime slag. During the blowing operation a careful watch is kept on the flame, and when the proper carbon content is obtained the air blast is stopped and the metal poured.

By means of the invention just described a low carbon ferro alloy is obtained. When applying my invention to the production of a. low carbon ferro chromium alloy I have found that such an alloy is secured without serious loss of chromium in the slag obtained from the converter. For example, in the production of ferro chromium containing 0.5% carbon the chromium content in the slag has been reduced from as found in the ordinary bessemerizing process, to 5%, as found when my process is used.

Having thus described my invention, what I claim is:

1. A method of decarbonizing ferro alloys by bessemerization comprising the addition to the usual materials charged into an electric furnace for the production of the .de-

sired ferro alloy a sufiicient quantity of titaniferous ore to protect the metal inthe alloy from oxidation during the smelting 'operation, then-charging this mixture into an electric furnace of the arctype and smelting the charge, then pouring the molten metal into a converter and simultaneously adding lime to such molten metal, and then subj ecting the molten metal to an air blast until the desired reduced carbon content is obtained.

2. A method of. decarbonizing ferro alloys by bessemerization comprising the addition to the usual materials charged into an electric furnace for the roduction of the desired ferro alloys, 0 a suflicient quantity of titaniferous ore to give the charge a titanium content varying from 1% to 10%, then charging this mixture into an electric furnace of the arc type and smelting the charge, then pouring the molten metal into a converterand simultaneously addin'g lime to such molten metal, and then subjecting the molten metal to an air blast until the desired reduced carbon content is obtained.

3. A method of decarbonizing ferro alloys by bessemerization comprising the addition to the usual materials charged in an electric furnace for the production of the desired ferro alloys of suflicient carbon to make a carbon content of from 6% to 10%, then adding suflicient silicon to make a silicon content of from 1% to 6%, then adding sufiicient titaniferous ore to make a titanium content of from 1% to 10%, then charging this mixture into an electric furnace of the arc type and smelting the charge, then pouring the molten metal into a converter and simultaneously adding lime to the metal in the converter, and then sub 'ecting the molten metal to an air blast untll the desired reduced carbon content is obtained.

* 4. A method of decarbonizing ferro alloys by bessemerization comprisin the addition to the usual materials charged into an electric furnace for the production of the desired ferro chromium ofa suflieient quantity of a titaniferous ore to protect the metal in the alloy from oxidation, then charging the mixture into an electric furnace of the arc type and smelting the same, then pourin the molten metal into a converter, and s1multaneously adding lime to such molten metal, and then subjecting the molten metal to an air blast until-the desired reduced carbon content is obtained.

In testimony whereof, I hereunto sign my name.

' HUGH o. SICARD. 

